This invention relates to photoplotters for exposing graphics on a photosensitive surface through the use of a movable beam of light so that only a small, discrete portion of the surface is exposed at any instant of time, and deals more particularly with such a photoplotter wherein the output beam flashes as it is moved to expose a line on the surface.
Photoplotters of the general type with which this invention is concerned are shown by U.S. Pat. No. 3,330,182; No. Re. 27,265; and No. 3,565,524. Photoplotters with flashing output beams are also known in the art and are shown, for example, by U.S. Pat. No. 3,903,527 and No. 4,170,745.
The general object of this invention is to provide an improved photohead of the type having a flashing output beam for use in exposing lines.
Other more particular objects of the invention are to provide a photohead having a simple, reliable means for producing a flashing output beam and including a constantly on, non-flashing light source such as an incandescent lamp, arc lamp or laser; wherein the duration and intensity of the beam during each flash may be readily controlled; wherein the photohead may be made of low mass so as to have a low inertia facilitating rapid acceleration and deceleration; wherein the photohead may be used to project differently colored beams of light for exposing differently colored lines on a color sensitive photosensitive surface; and wherein two or more beams from different light sources may be combined in the output beam to vary the intensity or color of that beam.
Still other objects of the invention are to provide a photohead of the foregoing character which may include a means for varying the size and shape of the light spot delivered to the photosensitive surface, and which may also include a beam rotating means to cause the light spot created on the photosensitive surface to maintain a desired orientation with respect to its path of motion relative to the photosensitive surface.
Other objects and advantages of the invention will be apparent from the following description and from the accompanying drawings describing and illustrating several embodiments of the invention.